1. Field of the Invention
This invention relates to apparatus for delivery of humidified gases therapy and in particular, though not solely to humidified Positive Airway Pressure (PAP) apparatus used in the treatment of Obstructive Sleep Apnea (OSA).
2. Summary of the Prior Art
OSA is a sleep disorder which affects an estimated 5% of the population in which muscles which normally hold the airway open, relax and ultimately collapse, sealing the airway. The sleep pattern of an OSA sufferer is characterised by repeated sequences of snoring, breathing difficulty, lack of breathing, waking with a start and then returning to sleep. Often the sufferer is unaware of this pattern occurring. Sufferers of OSA usually experience daytime drowsiness and irritability due to a lack of good continuous sleep.
In an effort to treat OSA sufferers, a technique known as Continuous Positive Airway Pressure (CPAP) was devised. A CPAP device consists of a gases supply (or blower) with a conduit connected to supply pressurised gases to a patient, usually through a nasal mask. The pressurised air supplied to the patient effectively assists the muscles to keep the patient's airway open, eliminating the typical OSA sleep pattern.
The use of a CPAP system is known to have side effects such as dehydration of the airways and nasal passages which may lead to Rhinitis (inflammation of the nasal passages). The side effects mean that the patient is less likely to comply with his or her CPAP therapy and the therapy itself may cause an increase in nasal resistance as a response to the high air flow, degrading the pressure level applied to the airway and thereby reducing the effectiveness of the therapy. Accordingly, humidified CPAP systems have been developed. One example is described in U.S. Pat. No. 5,537,997 assigned to Respironics Inc. in which a humidifier is incorporated with the CPAP system so that the patient receives humidified gases. Another example is shown in GB 2338420.
While these humidified systems improve patient comfort when properly used, inappropriate setting or lack of activation of the humidifier component of the CPAP system reduces the comfort benefits. It is known that patients or users are prone to failing to use the system where comfort levels are poor, with users frequently failing to comply within a structured regime of treatment.
In a first aspect the invention may broadly be said to consist in an apparatus for delivery of humidified gases therapy, said apparatus including:
a humidifier, said humidifier having a humidity setting selector, operable by said patient to set and adjust a desired humidity level,
a blower, said blower having a range of operating speeds, and delivering a substantially constant pressure across a wide flow range, for an unvaried operating speed,
a flow sensor providing an output indicative of flow delivered by said apparatus, means for producing user compliance data, calculated from said output of said flow sensor and said operating speed of said blower,
data recording means, said data recording means recording humidity data and said user compliance data, said humidity data indicative of the humidity of gases delivered by the apparatus,
an output interface means for outputting said recorded user compliance data and humidity data.
In a second aspect the invention may broadly be said to consist In a method of diagnosing causes of ineffective humidified gases therapy comprising the steps of:
retrieving logged humidity data and logged patient compliance data from an apparatus,
comparing said patient compliance data with said humidity data, and
determining inadequate or excessive humidity as a potential cause of said inadequat; treatment based on said comparisons.
In a third aspect the invention may broadly be said to consist in a method of improving efficacy of humidified gases therapy comprising the steps of:
retrieving logged humidity data and logged patient compliance data from an apparatus,
comparing said patient compliance data with said humidity data, and recommending alterations to said therapy based on said comparisons.